Temperature controller



v Api-i125, 1950 A. B. NEwToN TFnmm'rume: CONTROLLER Filed Nov. 4, 1943Gttorneg Patented Apr. 25,1950

s-l PATENT OFFICEI TEMPERATURE CONTROLLER Alwin B. Newton, Minneapolis,Minn., assigner to Regulator Com Minneapolis-Honeywell Minneapolll,

Pill! Minn., a mention of Delaware Application November'l. i943, Serial`No. 508,935

l. Claims. (Cl. I4-10.)

. Y l Temperature controllers actuated by a bellows and connected bulbiilled with a volatile iluld have long been used and have givencomparatively good satisfaction over relatively short' ranges oftemperature. However, such devices have not been used for long rangetemperature controllers because of the considerable variation indiflerential occasioned by the action of the lbulb and `bellows system.The pressure exerted by a renews and bulb arrangement sued with volatilenuid does not vary in straight line relationship with the temperature.With a particular bulb and bellows means, the pressure rise, or theforce exerted by the'bellows, varies at the low end of the temperaturescale by relatively small amounts -as the temperature changes; whereasat the upper end of the range of the device, the force exerted by thebellows increases considerably with like changes in temperature. Thisaction tends to give wider operating differentials at the bottom of therange of a temperature controller than at the top. Such an arrangementis inherently bad for cooling conditions, for in cooling, the highertemperatures represent light loads and the lower temperatures representheavier loads; therefore, with the temperature controller acting asabove outlined, short cycling would occur at the upper end of the rangeof the controller and unduefvariations in temperature would occur at thelower end of the range'. Ob-

, viously, the'more the range of the instrument is extended, the moretroublesome this condition In the past, this diiliculty has beenminimized by using only a comparatively short-portion of the potentialrange of the instrument to thereby minimizethe change of differential.This has vtend the usable range `of a single temperature controller. T

It is therefore an object of the present invention to `provide a longrange temperature controller actuated by a bellows and bulb system.

It is an object of this invention to provides control device responsiveto temperature wherein the operating differential may be maintainedreasonably uniform' throughout a wide `range oi temperature variation.

to extend the range of a temperature controller by controlling thevariation in differential of said controller.

It is also an object of the present invention to extend the range of atemperature controller by increasing the rate of the forces opposing theaction of the bellows as the control point is ad- Justed upwardly.

It is a i'urther object to control the diilerential change in atemperature controller by increasing the rate of forces opposing thebellows and supplementing same by friction.

It is an additional object to minimize the differential change in atemperature `controller by compensating for the change in rate oi theforce vexerted by the bellows by changing the rate of the means opposingsaid bellows as adjustments of the controller are tightened. l

It is an object to provide compensating means to modify the operatingdifferential of controls `to provide a temperature controller having anextended range which resembles, as nearly as possible, conventionalcontrollers so that the manufacturing and tooling costs maybe kept at aminimum.

These and other objects will become apparent Y upon a study of thefollowing specification and drawing in which: 4

Figure 1 is a side elevation of a temperature controller of thesortdescribed, housing parts being in section.

Figure 2 is an end elevation of the controller of Figure 1, a portionbeing broken away to show the internal construction. e

Figure 3 is a side elevation of a modiiled temperature controller,housing parts being in section.

Figure 4 is a side elevation of a further modifled temperaturecontroller, with housing parts in section. a

Figure 5 is a partial end elevation of the controller of Figure 4, laportion being broken away to show the internal construction.l

The temperature controller of Figures 1 and 2 comprises a housing Ilhaving attached at its bottom portion. a bellows device Il with anactuating member I2. Connected in sealed relation with bellows Il isbulb Il which contains a'nil It is a further object of the presentinvention 6o oi' volatile fluid, said bulb l; being the tempera- 3 turesensitive element of the device. Actuating member I2 coacts with leverI4, which fulcrums about member I5. Attached to lever I4 is arm memberI6 which actuates mercury switch I1.

The force exerted on lever I4 by member I2 is resisted by two springmeans which resist the action of the bellows device, one of the springmeans, 23, being operable through a pivoted lever in frictionalcontact-with the tilting lever means associated with the bellows device.The other spring means, I8, includes acoiled tension spring I9. Athreaded plug in one end of the spring I9 coacts with adjusting screw2|, and the other end of spring I9 coacts with lever means I4 throughpivot member 22. supplementing the action of spring means I8 is saidspring means 23 comprising a coiled tension spring 24. threaded plug inone end of spring 24 coacts with adjusting screw 26 and the other end ofsaid spring 24 is attached to arm 28 of lever 21. Lever 21 comprisessaid arm 28 and another arm 29 which frictionally contacts the undersideof one end of lever I4, when so adjusted. Lever 21 is pivoted aboutmeans 30.

The motion of lever I4 is limited by bottom stop 3I and upper stop 32.The adjustments of spring means I8 and 23 are indicated by means 33 and34 respectively.

The mercury switch I1 has an inherent operating differential that may bedened as the difference in angular degrees between the position in whichthe mercury will run to one end of the tube and the position in which itwill return to the first end of the tube. 'Likewise the actuating memberI6 must be moved through a predetermined angle to eiect movement of theswitch I1 through its differential. The difference in pressure withinthe bellows chamber II necessary to move the switch I1 through itsdifferential will depend on the total effective spring rate plus thefrictional drag between the arm 29 and the lever I4. If both springs I8and 23 are acting on the lever I4 the spring rate will remain constantregardless of the adjustment of spring.

tensions, but the frictional drag between the arm 29 and the lever ,I4will be proportional to the tension of spring 23. Hence the differencein pressure in the bellows II necessary to actuate the switch I1 throughits operating differential will increase if the screw 26 is adjusted totighten the spring 24, and will decrease if the tension of that springis reduced.

Asdifferent types of lls for the temperature sensitive bulb I3 havedifferent temperaturepressure characteristics, the comparative rates ofsprings I9 and 24 will depend on the diiferential ycharacteristicsdesired and the type of ill used.

Further, it is contemplated that more than two springs may be used andthe scale may be divided into more than two portions, the above examplebeing but one of many feasible arrangements within the scope of thisinvention.

An arm 35 is loosely suspended from a. pivot 36 near the upper end ofthe housing I0 and is provided with a pointer 31 at the bottom thereofcooperating with a mark 38 on the back of the housing for the purpose ofindicating when the instrument is in a proper vertical position so thatthe mercury switch I1 used will function correctly.

Operation of Figures 1 and 2 With the parts of the temperaturecontroller associated as above described, and assuming for the purposeof this description. that the bulb and vis effective throughout therange of the instrument and spring means 23 is effective only throughthe upper portion` of the range of the instrument, the particulardivision of the range being a matter of choice, and inuenced by thespring rates, the type of fill used, and other such factors. With onlyspring means I8 effective during the lower portion of the range of theinstrument, the minimum adjustment of spring means I8 may be assumed tobe at the point 100. The upper limit of the adjustment of spring meansI8 may be placed at 20; therefore spring means I8 alone may be adjustedto take care of any control point in the temperature range of to 20. Thecontrol point is raised in this lower portion of the range by increasingthe tension of spring means I8. While spring means I8 is being used forcontrol points in the range of 100 and 20, spring means 23 is soadjusted that arm 29 of lever 21 is out of contact with member I4.

As the control point is raised above 20, the adjustment of spring meansI8 is left at its 20 position and spring means 23 is adjusted to bringarm 29 of lever 21 into engagement with lever I4. By tightening springmeans 23, arm 29 supplements theaction of spring'means I8 and permitsraising the control point to the upper limit, +50", of the instrumentdescribed. Note that only spring means I8 is used for the lower portionof the range of the instrument .and spring means I8 plus spring means'23 is used for the upper portion of the range, all of the adjustmentsfor said upper portion being on spring means 23. In addition to thesupplementary force of spring means 23 acting through arm 29 oi' lever21, friction between arm member 29 and member I4 resists movement of armI4 in either direction and tends to widen the operating differential.This friction increases as spring means 23 is tightened, thus the eifectof friction on the differential is increased as spring means 23 isadjusted for higher control points. Obviously, the coefficient offriction of the friction surfaces influences the magnitude of the effectof said friction on the differential but, asa practical matter, thecoeiiicient is kept reasonably low by smoothly finishing said surfaces,this being necessary to avoid erratic operation and for uniformity inmanufacturing.

With spring means I8 only opposing the action of bellows II, theoperating differential narrows to some extent as the control point isadjusted upwardly by tightening spring means I 8. When spring means I8is supplemented by spring means 23, the operating dlierential iswidened, but as the control point is further raised. the -operatingdifferential again tends to narrow. However, as before stated, the forceof vspring means 23 is exerted through arm 29 to member I4, and thefriction due to the engagement of same tends to retard movement andthereby increases the differential with a net result that the operatingdifferential may be kept reasonably uniform or, depending on thecomparative spring rates and the used, actually increased as the controlpoint is aiusted upwardly. There is thus provided a temperaturecontroller capable of operating over a long range. Further, the presentcontroller gives superior results for cooling service by widening theoperating differential at the upper-lend of the scale and thuspreventing short s x cycling. lheabilitytocontroltheehangeofdiiierentialalso makespossible the narrowing ot the diiierential in the lower rangeso! the scale and-still maintain a workable differential at the upper endot the scale. The improvement made possible in the lower ranges of thecontrol scale In Figure 3 is shown a modiiied long range temperaturecontroller actuated by a volatile iluidillled bulb and bellows assemblysuch as previously described. Bellows device 4| has an operating member43 which bears against tui-- crumed member 44. Member 44 pivots abouttulcrum 4i attached to housing 40. Attached to member 44 is arm member44 which operates mercury switch means 4l. The force exerted Y on member44 by operating means 43 of bellows 4| is resisted by spring means 4I,said means comprising a coil spring 49. A plug 50 is fitted in one endot said spring 40 and an adjusting screw Il is threaded into said plug.An anchor means i2 coacts with member and theother end ot said spring4l. l

' Adjusting screw 5I coacts with lever member I3 pivoted to housing 4tby means I4, said lever Il havmg a horizontal arm 5l and a vertical armIl. The adjusting screw Il extends through a hole Il in arm II and thehead of said screw bears against a pivot member It which coacts with theupper side of said arm 5I. AA hole 59 is provided in housing 44 topermit access to the head of said screw 5| to permit movement of saidhead relative to said housing. The adjustment oi' spring means 4I isindicated kby pointer means III which extends out through housing 4l inthe conventional manner.' Said pointer 60 includes an offset portion toavoid spring means 6T, to be described. At the lower end of arm 66 isprovided a pivot portion 4I which coacts with a link l2, said link 62extending through an opening 84 in member 44 in pivotal relation to asharpened edge portion 83. Pivot portions 6| and 63 are preferablyarranged to be in alignment with member 44 when the left .end of memberV44l approaches bottom stop means' 6l and switch 41I is in a position tobreak a cooling circuit or the like. Scale adjustments are made and readwhen the parts are in the positions shown, uniformity in this matterbeing desired because of the slight movements of SII due to movement ofmember il and spring means 4l, as the bellows contracts and expands.Pivots 8i and may also be arranged to align with 44 when said member 44is in an intermediate position between the stops or may align with 44when theleft end of same approaches the upperstop and switch 41 is incooling circuit making condition. These various arrangements of pivotsil and 63 have little effect on the rate of change oi' the operatingdinerential although they may aiTect the amount of difrerential. v

A differential control comprises adjustable spring means il whichconsists of a tension spring 44 secured at one end to the extreme leften'd of horizontal arm 55d; a plug `69 being tted in the other end ofsaidspring. An adjustable screw means 'Il coacting with housing 4II lsthreaded into said plug 4l and furnishes means for adjusting the tensiono! said spring. Pointer means 1I. associated with said plug 4l. extendsthroughr 6 housing 4I to indicate the adjustment of means 41.

Operation In operation. with only spring means 4I opposing the action ofmember 43 of bellows 4l. the operating dinerential oi' the instrumentwould tend to become narrower as the control point is raised bytightening adjusting screw Il. This narrowing of the operatingdinerential would be due to the action of thell in the bulb and bellowsarrangement, as previously described. However, adjusting screw Il coactswith pivoted arm member 53. and a counterclockwlse force is exerted atpivot portion 6l of arm I8 when the adjusting sprint screw 5i istightened. This counter clockwise Y torce, so long as it is exerted inalignment with member 44, has no eiIect on the force required by member43 to operate said member 44. In the position shown of the parts, anunsatisiied cooling condition is indicated. and the pressure is high inbellows 4I. As conditions of cooling become satlsiied, and the pressuredecreases in 4I, spring means 48 tends to cause clockwise rotation o!member 44. This clockwise rotation is resisted by member 4I of bellows4l and is also resisted by the action of arm It and link 42. Because ofthe assistance of arm `I4 and link 82 in resisting the clockwise motionof member 44, the pressure exerted by bellows 4I may diminish more thanotherwise. As the adjusting screw 5| is tightened for higher controlpoints, the eiiect of arm 56 and link 62 upon member 44 increases, thuspermitting a greater diilference in pressure in bellows 4| betweensatisiled and unsatisfied condition as control points are raisedupwardly. As previously noted, the pressure difference caused by bellows4i and its associated bulb for umts of temperature change, increases asthe control points are raised; hence, it becomes necessary to providefor greater pressure diierences in the instrument at higher controlpoints if a reasonable and constant operating differential is to bemaintained, or if the diiIerential is to be widened at the upper controlpoints. As the instrument just described requires greater pressuredierences for operation at higher control point adjustments, it providesthe necessary modification of dinerential for a practical instrument. Itis noted that compensation` is provided throughout the entire range ofthe instrument in this modincation; hence, the present instrument notonly has desirable dinerential characteristics but may also be developedto use the full potentlalities oi the temperature sensitive means.

Upon adjusting the tension ot springmeans 61 by tightening adjustingscrew 10. theeiiect of arm 56 and link B2 on member 44 may be increasedand the operating differential thus further modiiled'. Tightening screw'Il has the same eifect on the operating diierentlal as tighteningadjusting screw 5i but note that in this case only the differential ischanged whereas when `screw Il is adjusted, both the diiierential andcontrol. points are altered.- Pointer 1i indicates the adjustment of thedifferential and pointer tl indicates the adjustment of the controlpoint.

Figures 4 and 5 Figures 4 and 5 show a further modined long rangetemperature controller comprising a housing I0, to which is attached abellows Il, said bellows having an operating member l2. Bellows '4I isactuated by connected bulb I4 illled with a volatile'uid. Member 42coacts with fulcrumed lever 84. which pivots about fulcrum member 88.Member 84 has attached thereto, arm 88 which operates mercury switchmeans 81. The action of operating member 82 of bellows 8| is resisted byspring means 88 comprising a' coil spring 89 and a rotatable, spirallygrooved member 90, said member 90 being rotated by means 9|. Spirallygrooved member 90 is threaded into one end oi spring 89 and may beadjusted to pull same upwardly and tighten same. In addition totightening said spring 89, the effective length of the spring islessened, thus its rate is increased. Adjustment indicating means 88,similar to 33 and 34 of Figures 1 and 2, is attached to the upper end ofspring 89, and not only indicates said adjustment but also restrainstwisting of said spring, due to friction between said spring androtatable member 90, while adjustments are being made.

The other end of the spring 89 coacts with lever means 92, similar tolever means 21 of Figure 2.l Lever means 92 frictionally coacts withmember 84 in the same manner as 21 of Figure 2, through contact portion94, whereby the frictional effect of member 92 relative to member 84 isincreased as 'spring means 98 is adjusted for higher control points.

Operation In operation, at low control'points, spring means 88 isrelatively loose, and due to the low pressure, there is little frictionbetween member 92 and member 84 and member 82 may operate 84, 86 andmercury switch 81 with a predetermined oper-ating diierential. As thecontrol point is raised by adjusting means 9|, spiraliy .grooved member98 is threaded into spring 89 and tightens same. The tendency of spring89 t twist asspirally grooved member 90 is threaded thereinto isresisted by indicating means 93 which is attached to the upper end ofsaid spring 89. In addition to tightening the spring, the effectivelength of spring 89 is lessened, as previously noted. The increase inspring rate occasioned by shortening the effective length of the springoffsets the increased rate of pressure build-up in bellows 8| astemperatures are increased, and thereby tends to maintain a uniformoperating differential, or one having other desired characteristics. Inaddition, friction between member 92 and member 84 increases as thetension of spring 89 is increased and this increase in friction, inconjunction with the increased spring rate, tends to provide widerdifferentials as the control point is raised. A judicious choice of thespring used and the pitch of member 90 permits suitable control of thedifferential characteristics including a diminished rate of change ofdifferential, a uniform differential or `an increasing differential ascontrol points are raised. The friction surfaces may also be altered tochange the diierential characteristics but it is generally desirablethat such surfaces be uniformly smooth.

By thus providing a controller wherein the forces opposing the operatingmember of a bulb and bellows assembly are increased in a manner tocompensate for the increased rate of presi sure rise in the bellowsassembly as the control point of temperature is increased, it becomespractical to use such a controller over a wide range of temperature. TheAmaintenance of a reasonably uniform operating diierential makestheinstrument effective as a cooling control but the actual widening ofthe differential with higher control points is often still moredesirable for cooling control' means.

In each of the examples shown, it is seen that the increased rate ofpressure build-up in a bulb and bellows operated temperature controllercan be oil'set, or the effects of same modified, by opposing the actionof said bulb and bellows arrangement with force exerting means having avariable rate. In addition to greatly extending the range of operationof such a temperature controller, superior operating characteristics ofcooling equipment also results. The ability to use a reasonably narrowdifferential at the lower ranges of the controller permits themaintaining of reasonably uniform temperatures, whereas the preventingof undue narrowing of the differential as the control temperatures areraised,

prevents the unduly rapid stopping and starting of the equipment knownas "short cycling.

It is also contemplated that the present means for modifying theoperating differential of temperature controllers, limit controls or thelike, may be used with condition responsive means other than bulb andbellows devices. In controllers using an expanding uid. solid, or othertemperature responsive means, the present invention may be used toprovide suitable diierential characteristics, especially for cooling,wherein the differentials are preferably relatively wide at the upperend of the scale and relatively narrow at the lower end of said scale.

Because the present means permits considerable control of differentials,it becomes more feasible to use vacuum fills in bulb and bellows devicesthan previously. The use of such fills has been limited in the past dueto the considerable rate of change of pressure relative to temperaturechanges. Now, the safety features of such fills may be enjoyed whiledesirable operating characteristics of the controlled equipment aremaintained.

`The above examples of the present invention are intended to beillustrative only and are not to be considered in a limiting sense, thescope of the invention beingdetermined by the following claims.

I claim as my invention:

l. In a pressure responsive device, in combination. means dening anexpansible chamber, a member positioned by said chamber, control meansactuated between two operative positions by said member, a spring actingon said member in opposition to the force due to the expansible chamber,differential determining means responsive to the force of said springapplying a, further force on said member tending to resist movementthereof in either direction, between positions corresponding to the twooperative positions of said control means and means for adjusting saidspring to vary the force applied to said member and tosaid differentialdetermining means by said spring.

2. In a pressure'responsive device, in combination, means defining anexpansible chamber, a member positioned by said chamber, control meansoperated by said member or movement thereof between two predeterminedpositions, a spring acting on said member between the predeterminedpositions in opposition to the force due to said expansible chamber,differential determining means acted on by said spring applying afurther force on said member tending to resist movement thereof betweenthe limits of the range of movement When'moved in either direction, andmeans for adjusting said spring to vary the force 'applied to saidmember by said spring and to vary simultaneously the eflect of saiddifferential determining means on said member.

`il. In a pressure responsive device, in combination, means deiining anexpansible chamber, a rst lever positioned by said chamber, controlmeans operated by said iirst lever, a second lever adapted frictionallyto engage said ilrst lever, said levers being pivoted on separateaxesdisposed to cause substantial relative movement between the points ofcontact between said second lever and said ilrst lever on movement ofsaid levers, a spring for biasing said second lever into engagement withsaid ilrst lever, and means for adjusting the biasing force of saidspring for determining the diilerential between the forces supplied bysaid chamber necessary to move said levers in opposite directions.

4. In a pressure responsive device, in combination, means deiining anexpansible chamber, a iirst lever positioned by said chamber, controlmeans operated by said ilrst lever, a second lever adapted to engagesaid rst lever to oppose expansion of said chamber, a spring for biasingsaid second lever into engagement with said first lever, said secondlever being pivoted on an axis disposed to cause substantial relativemovement and a resulting frictional drag between the points of contactbetween said second lever and said iirst lever as said ilrst lever ismoved, and means for adjusting the biasing force of said spring fordetermining the total force that must be applied by said chamber as wellas the differential between mined range of movement in opposition to theforce due to said expansible chamber, a, link having a ilrst' pivot insaid member and a second pivot that lies in a plane at right angles tothe direction of movement of the iirst pivot when said member is at onepoint in its range of movel spring.

the forces supplied by said chamber necessary to 'move said levers inopposite directions.

5. In a pressure responsive device, in combination, means defining anexpansible. chamber, a rst lever positioned by said chamber, controlmeans actuated by the two operative positions by said member, a secondlever adapted frictionally to engage said rst lever, said levers beingpivoted on separate axes disposed to cause substantial `sliding movementbetween the points of contact between said levers on movement thereof,a. spring for biasing said tlrst lever into engagement with said secondlever, means for adjusting the biasing torce of said spring, a secondspring acting on said member and tending to cause collapse of saidexpansible chamber, and means for adjusting the force applied by saidsecond spring.

6. In a pressure responsive device, in combination, means dening anexpansible chamber, a

member positioned by saidexpansible chamber, control means actuatedbetween two operative positions by said member on movement thereofthrough a predetermined range, a iirst spring opposing movement of saidmember by said expansible chamber throughout the range of movement,means for adjusting the force oi said first spring, a second springadapted to act on said member to resist movement thereof in eitherdirection throughout the range of movement of said member invmoving"said control means between said two operative positions, andmeans fordissaid second spring from said member. '1. In a pressure responsivedevice, in combination, means deningan expansible chamber, a memberpositioned by said chamber, control means operated by saidmember onmovement thereof through a predetermined, range, a spring acting on saidmember throughout the predeter- 1o y 8. In a pressure responsive device,in combination, means deiining an expansible chamber, a memberpositioned by said chamber, control means operated by said member onmovement thereof through a predetermined range, a spring acting on saidmember throughout the predetermined range of movement in opposition tothe force due to said expansible chamber, a link pivoted in said memberand having a second pivot biased by said spring, said spring biasingsaid member through said link to a' position in which said control meansis positioned within said predetermined range, and means foradjustingthe force of said spring.

9. In a pressure responsive device, in combination, means dening anexpansible chamber, a member positioned through a predetermined range ofmovement by said chamber, control means operated by said. member, aspring having a rst end connected to said member for directly opposingmovement thereof by said chamber, and having a second end operativelyconnected to a link and adapted, through said link, to bias said memberto one point in its range of movement, and means for adjusting the forceof said spring.

10. In a. pressure responsive device, in'combination, means defining anexpansible chamber, a member positioned by said chamber, control meansoperated by said member, a lever adapted irictionally to engage saidmember, said lever being pivoted on an axis disposed to cause relativemovement between the points of contact between said lever and saidmember on movement of said lever, a spring for biasing said lever intoengagement withsaid member, and means for adjusting the biasing force ofsaid spring and for simul- Y taneously changing the eilective length ofsaid spring-` ALWIN 2B. NEWTON.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 1,023,480 Beck et al. Apr. 16,1912 f 1,492,312 Penn Apr. 27, 1924 1,618,963 Knaak Feb. 22, 19271,851,629 Phelan g Dec. 8, 1927 1,681,157 Eggleston Aug. 14, 19281,768,625 Olsen July 1, 1930 2,070,108 Bargeboer Feb. 9. 1937 2,085,3001 Dillman June 29. 1937 2,159,513 Taylor May 23, 1939 2,267,688 LandonDee. 23, 1941.V

